The $3.6 million acute mental health ward at Wakari Hospital opens on Monday, replacing the Dunedin Hospital facility.
In addition, a purpose-built four-bed medium security facility for those with intellectual disability also opens on Monday, at Wakari Hospital.
Southern DHB mental health and community services general manager (Otago) Elaine Chisnall said there was "no comparison" between the old and new acute mental health wards.
The 16-bed acute ward, which is part of the 16-project $24.38 million redevelopment for Dunedin and Wakari hospitals, is flooded with natural light, has plenty of space for activities, and lots of outdoor space and decks. Each room has a bathroom en suite.
The Dunedin Hospital ward was dark and full of awkward "nooks and crannies", which made it difficult to staff. The old ward had no outdoor space, as it fronted the street, she said.
The new ward was better for special patients like mothers and babies, youth, and those with eating disorders.
The ward would be known as 9c, rather than 1a, as it was at Dunedin Hospital.
The old 1a ward would be redeveloped as managers' offices, work which would begin early next month, facilities and site development manager Warren Taylor said.
The other facility opening on Monday - Helensburgh Cottage - is a four-bed medium-secure unit for intellectually disabled people.
The $2.31 million South Island-wide facility was directly funded by the Ministry of Health.
Two residents move in on Monday.
The unit, for which the DHB has hired about 13 full-time staff, was designed as an interim step between secure care and the community.
Ms Chisnall said it was exciting to see the two projects come to fruition.
